1. Field of the Invention
The present invention generally relates to semiconductor formation technologies using capacitive-coupled plasma CVD, and particularly relates to a method of forming fluorine-doped low-dielectric-constant silicon oxide films having a low dielectric constant and high thermal stability.
2. Description of the Related Art
In semiconductor integrated circuits, miniaturization has made progress aiming at increasing speeds and providing more sophisticated features. In multilevel interconnect technologies, aluminum had been conventionally used. As the miniaturization had advanced and interconnects had become minute and long, however, problems have emerged including electromigration during use, i.e., disconnection accidents caused by increased current density relative to minute and long interconnects, or signal delays caused by the resistivity of aluminum or a dielectric constant of an insulating film.
Because copper is resistant to disconnection accidents and has further small resistivity, copper interconnect technology has been developed for future interconnects. Because application of conventional manufacturing processes to copper interconnects, however, is difficult, putting the copper interconnect technology to practical use has not been progressed easily. In 1997, Cu trench filling interconnect technology called “Dual-Damascene”, in which a trench is formed in an interlevel layer by etching and is backfilled by electroplating a Cu thin film and the entire surface is polished by CMP (Chemical Mechanical Polishing), was developed respectively by IBM and Motorola. In conventional methods, an AI film was etched to form a convex interconnect pattern; an interlayer was filled with an insulating film. As against this, the Damascene interconnect technology deposits a Cu thin film on the entire surface including a trench formed in a planar interlayer insulating film; the surface of the insulating film is subjected to CMP for polishing so that Cu remains only in a trench portion to create an interconnect.
Consequently, use of capacitive-coupled plasma CVD apparatuses for forming low-dielectric-constant insulating films has become possible in place of high-priced HDP (high density plasma) apparatuses which conventionally were essential for filling an interlayer with an insulating film; as disclosed in Japanese Patent Laid-open No. 2002-141348, an embodiment using SiH4 as a silicon source gas, SiF4 as a silicon and fluorine source gas, and N2O as an oxidizing gas is disclosed.